diff --git a/src/Makefile.shlib b/src/Makefile.shlib
index 732338caa4..8efa69db1d 100644
--- a/src/Makefile.shlib
+++ b/src/Makefile.shlib
@@ -6,7 +6,7 @@
 # Copyright (c) 1998, Regents of the University of California
 #
 # IDENTIFICATION
-#    $PostgreSQL: pgsql/src/Makefile.shlib,v 1.103 2006/04/19 16:32:08 tgl Exp $
+#    $PostgreSQL: pgsql/src/Makefile.shlib,v 1.104 2006/04/28 02:53:20 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -107,11 +107,11 @@ ifeq ($(PORTNAME), darwin)
   ifeq ($(DLTYPE), library)
     # linkable library
     DLSUFFIX		:= .dylib
-    LINK.shared		= $(COMPILER) -dynamiclib -install_name $(libdir)/lib$(NAME).$(SO_MAJOR_VERSION)$(DLSUFFIX) $(version_link) -multiply_defined suppress
+    LINK.shared		= $(COMPILER) -dynamiclib -install_name $(libdir)/lib$(NAME).$(SO_MAJOR_VERSION)$(DLSUFFIX) $(version_link) $(exported_symbols_list) -multiply_defined suppress
   else
     # loadable module (default case)
     DLSUFFIX		:= .so
-    LINK.shared		= $(COMPILER) -bundle
+    LINK.shared		= $(COMPILER) -bundle -multiply_defined suppress
   endif
   shlib			= lib$(NAME).$(SO_MAJOR_VERSION).$(SO_MINOR_VERSION)$(DLSUFFIX)
   shlib_major		= lib$(NAME).$(SO_MAJOR_VERSION)$(DLSUFFIX)
@@ -186,7 +186,7 @@ ifeq ($(PORTNAME), irix)
 endif
 
 ifeq ($(PORTNAME), linux)
-  LINK.shared		= $(COMPILER) -shared -Wl,-soname,$(soname)
+  LINK.shared		= $(COMPILER) -shared -Wl,-soname,$(soname) $(exported_symbols_list)
 endif
 
 ifeq ($(PORTNAME), solaris)
diff --git a/src/interfaces/ecpg/ecpglib/Makefile b/src/interfaces/ecpg/ecpglib/Makefile
index a5ce3b39c0..91542fe297 100644
--- a/src/interfaces/ecpg/ecpglib/Makefile
+++ b/src/interfaces/ecpg/ecpglib/Makefile
@@ -4,7 +4,7 @@
 #
 # Copyright (c) 1994, Regents of the University of California
 #
-# $PostgreSQL: pgsql/src/interfaces/ecpg/ecpglib/Makefile,v 1.38 2006/01/17 19:49:23 meskes Exp $
+# $PostgreSQL: pgsql/src/interfaces/ecpg/ecpglib/Makefile,v 1.39 2006/04/28 02:53:20 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -25,7 +25,7 @@ override CFLAGS += $(PTHREAD_CFLAGS)
 LIBS := $(filter-out -lpgport, $(LIBS))
 
 OBJS= execute.o typename.o descriptor.o data.o error.o prepare.o memory.o \
-	connect.o misc.o path.o exec.o \
+	connect.o misc.o path.o exec.o thread.o \
 	$(filter snprintf.o, $(LIBOBJS))
 
 SHLIB_LINK = -L../pgtypeslib -lpgtypes $(libpq) \
@@ -46,7 +46,7 @@ include $(top_srcdir)/src/Makefile.shlib
 # necessarily use the same object files as the backend uses. Instead,
 # symlink the source files in here and build our own object file.
 
-path.c exec.c snprintf.c: % : $(top_srcdir)/src/port/%
+path.c exec.c snprintf.c thread.c: % : $(top_srcdir)/src/port/%
 	rm -f $@ && $(LN_S) $< .
 
 path.o: path.c $(top_builddir)/src/port/pg_config_paths.h
@@ -62,7 +62,7 @@ installdirs:
 uninstall: uninstall-lib
 
 clean distclean maintainer-clean: clean-lib
-	rm -f $(OBJS) path.c exec.c snprintf.c
+	rm -f $(OBJS) path.c exec.c snprintf.c thread.c
 
 depend dep:
 	$(CC) -MM $(CFLAGS) *.c >depend
diff --git a/src/interfaces/libpq/Makefile b/src/interfaces/libpq/Makefile
index ff29e7c12a..2a1f76e712 100644
--- a/src/interfaces/libpq/Makefile
+++ b/src/interfaces/libpq/Makefile
@@ -5,7 +5,7 @@
 # Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
 # Portions Copyright (c) 1994, Regents of the University of California
 #
-# $PostgreSQL: pgsql/src/interfaces/libpq/Makefile,v 1.143 2006/04/11 20:26:40 neilc Exp $
+# $PostgreSQL: pgsql/src/interfaces/libpq/Makefile,v 1.144 2006/04/28 02:53:20 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -16,8 +16,8 @@ include $(top_builddir)/src/Makefile.global
 
 # shared library parameters
 NAME= pq
-SO_MAJOR_VERSION= 4
-SO_MINOR_VERSION= 2
+SO_MAJOR_VERSION= 5
+SO_MINOR_VERSION= 0
 DLTYPE= library
 
 override CPPFLAGS :=  -DFRONTEND -I$(srcdir) $(CPPFLAGS) -I$(top_builddir)/src/port
@@ -125,6 +125,31 @@ $(srcdir)/blibpqdll.def: exports.txt
 	echo '; Aliases for MS compatible names' >> $@
 	sed -e '/^#/d' -e 's/^\(.* \)\([0-9][0-9]*\)/    \1= _\1/' < $< | sed 's/ *$$//' >> $@
 
+# Where possible, restrict the symbols exported by the library to just the
+# official list, so as to avoid unintentional ABI changes.  On recent Darwin
+# this also quiets multiply-defined-symbol warnings in programs that use
+# libpgport along with libpq.
+
+ifeq ($(PORTNAME), darwin)
+$(shlib): exports.list
+
+exports.list: exports.txt
+	$(AWK) '/^[^#]/ {printf "_%s\n",$$1}' $< >$@
+
+exported_symbols_list = -exported_symbols_list exports.list
+endif
+
+ifeq ($(PORTNAME), linux)
+$(shlib): exports.list
+
+exports.list: exports.txt
+	echo '{ global:' >$@
+	$(AWK) '/^[^#]/ {printf "%s;\n",$$1}' $< >>$@
+	echo ' local: *; };' >>$@
+
+exported_symbols_list = -Wl,--version-script=exports.list
+endif
+
 # depend on Makefile.global to force rebuild on re-run of configure
 $(srcdir)/libpq.rc: libpq.rc.in $(top_builddir)/src/Makefile.global
 	sed -e 's/\(VERSION.*\),0 *$$/\1,'`date '+%y%j' | sed 's/^0*//'`'/' < $< > $@
@@ -147,7 +172,7 @@ uninstall: uninstall-lib
 	rm -f '$(DESTDIR)$(includedir)/libpq-fe.h' '$(DESTDIR)$(includedir_internal)/libpq-int.h' '$(DESTDIR)$(includedir_internal)/pqexpbuffer.h' '$(DESTDIR)$(datadir)/pg_service.conf.sample'
 
 clean distclean: clean-lib
-	rm -f $(OBJS) pg_config_paths.h crypt.c getaddrinfo.c inet_aton.c noblock.c pgstrcasecmp.c snprintf.c strerror.c open.c thread.c md5.c ip.c encnames.c wchar.c pthread.h
+	rm -f $(OBJS) pg_config_paths.h crypt.c getaddrinfo.c inet_aton.c noblock.c pgstrcasecmp.c snprintf.c strerror.c open.c thread.c md5.c ip.c encnames.c wchar.c pthread.h exports.list
 	rm -f pg_config_paths.h	# Might be left over from a Win32 client-only build
 
 maintainer-clean: distclean